The goal of this project is to elucidate the reversible and irreversible morphological alterations which may occur in the cells lining the cochlear duct of the inner ear after its having been subjected to noise or chemical trauma, ischemia, anoxia or hypoxia. The possibility of changes in permeability of these cells or the junctions between them following different experimental treatments will also be investigated. The ultimate goal of this work is to elucidate the mechanisms of injury of various traumas to the inner ear. Evaluation of demaged inner ears will include an overall survey of the embedded flat preparations by phase contrast microscopy so that complete cell counts can be made and percentages of missing or severely damaged cells can be calculated. This will be followed by sectioning of selected areas of damage at radial, horizontal or tangential angles for light or electron microscopic examination.